Polymers with improved properties and process therefor

ABSTRACT

Modified polymers, praticularly polyolefins having improved flow and in some instances improved adhesion properties over that of a polymeric, e.g. polyolefin, base stock used as a starting material, are produced by a controlled reaction often involving degradation in an extruder, in which an initiator is injected under conditions of either maximum distribution or intensive mixing wherein appreciable rheological, i.e., molecular weight distribution, changes in said base polymer occur. In some embodiments monomers are also grafted to said base stock, during said degradation process. In such instances, exceptional, novel, grafted polymers with high melt flow properties and other useful properties are obtained.

United States Patent .[191

Steinkamp et al.

POLYMERS WITH IMPROVED v PROPERTIES AND PROCESS THEREFOR Inventors:Robert A. Steinkamp; Thomas J.

Grail, both of Baytown, Tex.

Exxon Research and Engineering Co., Linden, NJ.

Filed: Apr. 3, 1972 Appl. No.: 240,494

Related US Application Data Continuation-impart of Ser. No. 132,838,April 9, 1971, abandoned.

Assignee:

US. Cl. 260/878 R, 260/878 B, 260/885, 264/176 R, 425/376 Int. Cl. C08f15/00 Field of Search 425/376; 264/176; 260/878 R References CitedUNITED STATES PATENTS 4/1965 Nowak et a1 260/878 R 4/l965 Jones et al.260/878 R 8/1966 Nowak 260/878 R 3/1972 Favie et al. 260/878 R 10/1972Schrage et a1. 260/878 R 10/1972 Schrage et al. 260/878 R 10/1972Schramm et al. 260/41 AG [451 Jan. 21, 1975 FOREIGN PATENTS ORAPPLICATIONS 742,340 11/1969 Belgium 260/878 R 1,042,178 9/1966 GreatBritain 260/94.9 GD

OTHER PUBLICATIONS ASTM D 1238-62T, Measuring Flow Rates ofThermoplastics by Extrusion Plastometer.

Primary Examiner-Joseph L. Schofer Assistant Examiner-A, HollerAttorney, Agent, or Firm-David A. Roth [57] ABSTRACT Modified polymers,praticularly polyolefins having improved flow and in some instancesimproved adhesion properties over that of a polymeric, e.g. polyolefin,

80 Claims, 3 Drawing Figures PROCESS THEREFOR This application is acontinuation-in-part of Ser. No. 132,838 filed Apr. 9, 1971', nowabandoned, entitled "Polyolefin Acrylic Acid Graft Copolymers.

BACKGROUND OF THE INVENTION Extruders have been used conventionally formany years to process all types of polymeric materials and especiallypolyolefins. Generally, the polymer is melted and worked to some extentin the extruder and conveyed to a particular molding means so that it isin the proper state to be handled by that specific, means.

In recent years, it has become known that various chemical reactions andmodifications can take place when a polymer passes within the extruder.These modifications, in a manner, are hitching'a ride or piggybacking ona polymer which is already being routinely processed. Thus it is atag-along process. The modifications can be accomplished in such a waythat significant changes in the polymer composition and/or rheology canbe effected.

There are numerous patents on such techniques of modifying polymers andmany of these are specifically directed to the grafting of monomers topolymers that are being still processed. This background disclosure isrestricted to those which are believed most relevant.

Very basic is British Pat. No. 679,562 which shows graft polymerizationto polymers taking place when the polymer is subjected to suitablemechanical working such as high-speed stirring. shaking, milling,kneading, grinding, ultrasonic vibrations or passage through filters orcapillary tubes at high linear velocities, all of which lead todegradation of the polymer and create reactive sites.

U.S. Pat. Nos. 3,177,269 and 3,177,270 are pertinent patents whichdisclose the formation of graftcopolymers by adding initiator andmonomer to a polymer as it is being extruded. The polymer is malaxed" tosuch a low degree that no degradation takes place.

US. Pat. No. 3,013,003 also discloses polymer degradation in an extruderand utilizes a stabilizer to prevent undue degradation. US. Pat. No.3,270,090 is a variant of US. Pat. No. 3,177,269 in which the polymer ispre-irradiated before being subjected to extru- SIOI'I.

U.S. Pat. Nos. 3,563,972 and 3,551,943 are relevant to polymermodification and extrusion using an oxygen-containing gas as aninitiator to cause polymer breakdown at relatively high temperatures andwithout any special mixing modification. British Pat. No. 1,217,231relates to grafting modifications wherein the amount of grafted polymerand homopolymer are controlled in some predefined ratio. British Pat.No. 1,042,178 teaches the preparation of modified polyolefins byshearing at extremely high shear rates in screw extruders, high-speedmills, roll mills and the like at a shear rate of at least 1,500reciprocal seconds.

Belgium Pat. Nos. 742,340, 742,338, 742,272 and 742,339 also relate tografting processes of interest.

As will be seen hereinafter, none of these disclose, hint or suggest inany manner whatsoever Applicants novel, unique and unobvious process andapparatus for modifying in a most unusual and desirable manner a polymerfeedstock to in many instances result in novel polymers with very usefulproperties.

SUMMARY OF THE INVENTION The invention relates to the formation and useof a special reaction zone within an extruder wherein reactionconditions can be chosen and controlled in order to effect: (I)instantaneous, intensive mixing of added reactants with a polymer or (2)intensive distribution of added reactants to a polymer, both of which inturn allow ready achievement of special rheological modifications of apolymer passing through said extruder.

Three especially important process parameters that can be controlled arethe shear. pressure and temperature within very short time periods.Applicants discovery of how to effect such controls leads to the severalunobvious and useful features of the invention.

Moreover, in a preferred embodiment, auxilliary reactants are introducedinto that zone under conditions where maximum effects occur withinminimum time parameters. Not only can a polymer be modified in terms ofits rheology, e.g., molecular weight and flow characteristics, butit-can also be simultaneously modified in terms of chemicalmodifications. This involves chemically reacting additional materialstherewith, especially to form novel grafted, shorter chain lengthpolymers from the base polymers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic view of onepreferred extruder apparatus embodiment of the invention for carryingout the process of the present invention wherein an initiator is addedto a decompression zone;

DESCRIPTION OF THE PREFERRED EMBODIMENTS It has been discovered andforms the substantial conceptual basis of this invention thatextraordinary process and product benefits relating to polymermodifications can be achieved by the formation and use of specialreaction zones and conditions within an extruder. Relatively lowtemperatures and high throughputs can be used. Furthermore, graftedproducts resulting therefrom are novel and possess unusual properties.Also, the economics of the process are quite improved.

Fundamentally, the invention resides in the discovery and utilization ofeither of two essential controlling factors in extruder reactionoperations. That is, one of these factors is that in order forsignificant modifications to be made to polymers being processed underhigh pressure, the reagent or reagents which are to interact with thepolymer must be extraordinarily thoroughly and intensively mixed withthe polymer over a very short interval of time. Thus, a much higherorder of magnitude of mixing is required than occurs when theteachingsof the art relevant to the introducing of a modifying reactantin conventional extruder operations are consulted.

In order to accomplish this highly,'intensive mixing or dispersion inthe extremely short periods of time, it was discovered and is one of theessential features of this invention that under pressure conditionsintensive.

3 extremely good mixing is obtained by utilizing a high shear-thin filmzone to provide the necessary mixing.

In essence, in this embodiment, an instantaneous, high intensity mixingzone is provided where an extremely high degree of mixing occurs in avery short period of time. In its simplest aspects, mixing can occurunder two different general types of conditions. These are extensivemixing and intensive mixing. They are defined as follows:

Extensive Mixing The material is constantly changing in its flowdirection according to statistical laws. so that each particle movessometimes on the surface and sometimes in the body of the mass ofmaterial. intensive Mixing Adjacent layers of materials have differentspeeds, i.e., there is a velocity gradient or shear rate between them,thus the mixing effect is due to the displacement of layers with respectto one another.

In the intensive, instantaneous high pressure, thin film high shearmixing zone feature of the invention, either or both of these types ofmixing occur with great intensity for relatively short periods of time.

One important feature of the invention has been discussed. It relates toeffecting significant changes during normal operation of an extruderwith at least the high pressures after the first stage metering zone.

Another very important aspect of the invention is based on adiametrically opposed principle. It is grounded on the followingconsideration. Commonly in extruder design, toward the end of theextrusion run, reduced pressure areas with vents are provided forventing off any volatiles formed during the extrusion process.

The essence of this facet ofthe invention is the recognition that one ormore decompression zones, i.e., reduced pressure zones accompanied byinjection orif'tces or conduits should be provided at a point where thepolymer is in a molten state.

This provides excellent, efficient reactions when reactants (preferablyfluid) are introduced in the reduced pressure zone under a pressurehead. Because of the reduced pressure, the reactants are immediatelydistributed over the total surface area of the molten polymer.

Moreover, in this process of the invention and means for carrying outsuch process, the reaction conditions accompanying either the pressurereduction embodiment or the high shear-thin film high pressureembodiment are also closely controlled. That is. temperature and meltviscosity of the polymer are controlled. Moreover, materials can beadded to another portion of the extruder prior to the reaction, becomemixed by extruder action, and thence conveyed to the reaction zone wherethey are available to participate in the reaction.

There are some preferred but optional additional features to theinvention which tend to improve the quality of the product.

One of these is the concept of sealing or capping both the highpressure-high shear reaction zone or the low pressure reaction zone witha device such as a blister, defining the completed reaction portion ofthe reaction zone. This is generally used in conjunction with asubsequent pressure relieving vent.

The preferred embodiment of such a device or blister is an enlargedcross-sectional portion of a screw root 4 which prevents gaseousreactants from easily leaving the reaction zone.

Preferably, the capping of the reactants is accompanied by a subsequentventing under reduced pressure so that vaporous components are removed.The capping also prevents vaporous reactants from being prematurelyremoved from the reaction zone.

Venting serves to prevent undesirable pressure buildup, corrosion causedby reactive vapors, odoriferous products, corrosive products, easilydegradable products and the like.

While the process of the invention is applicable to all polymers capableof being processed by an extruder. particularly thermoplastics such asnylons, polyesters, polycarbonates, engineering plastics, and aeetals.it is especially useful for C C preferably C -C polyolefins includingcopolymers of olefins with other monomers such as vinyl monomers inwhich the predominant constituent is the olefinic portion.

The process is also useful for elastomers, particularly polyolefins, butcan include silicone clastomers and the like. Furthermore, a distinctionshould be drawn between polymers whose properties are largely detrminedby the ethylene content and those polymers whose properties are largedetermined by their (I, to C olcfinic content.

This distinction is primarily evidenced in the fact that polyethyleneand ethylene-containing polymers tend to simultaneously cross-link anddegrade under some of the conditions in the reactor under which C andabove polyolefins would not cross-link but would tend to degrade.

Therefore, in the description of the invention as follows, from time totime certain differences in the applicable process conditions must beemployed when the primary characteristics of the polymer are determinedas a result of its ethylene content.

It is also to be noted that the process of the invention is applicableto elastomers of all classes which are capable of being handled by anextruder. Examples include natural rubber, polyisobutylene, butylrubber, chlorobutyl rubber, polybutadiene, butadiene-styrene rubber,ethylene-propylene elastomers, ethylenepropylene diene terpolymerelastomers and mixtures thereof with each other and with thermoplasticpolymers. Blends of elastomers and plastics in any portions particularlybenefit from being processed by the technique of the invention.

Polyolefins, both plastics and elastomers, in particular but also otherthermoplastics are used in many end uses where it is desired that theyhave the characteristics of being able to flow well during processing.This is especially true for the production of films, fibers, injectionmoldings and the like.

But many polymeric rheological properties depend not only on the averagemolecular weight of the polymer but also the molecular weightdistribution (as measured by die swell) of the individual polymermolecules within the mass. Thus. it is well known that a polymer havinga narrow molecular weight distribution will behave differently from asubstance having the same general molecular weight but a much widermolecular weight distribution.

For a great many commercial applications, narrow molecular weightdistributions are more desirable than wide ones. For some elastomers andlow molecular weight plastics, M w/M n is useful for measuring molecularweight distribution. But die swell (defined hereafter) is a much moreuseful measure. See US. Pat. No. 3,562,804 for a description ofmolecular weight distribution using M w/M n as a standard. In general,narrow molecular weight distributions indicate a trend toward lowerviscosities and improved flow properties.

Plainly, the best way of trying to obtain such desirable narrowmolecular weight distribution would be direct synthesis of the material.That is, one would desirably control the polymerization in such a waythat the desired narrow molecular weight distribution is obtained.Nevertheless, no really effective way of doing this during the synthesisof the polymer is known.

Therefore, conventional techniques of trying to achieve molecular weightchanges have taken the route of heating at high temperatures in order tothermally degrade the molecules. This can result in unpleasant odorswith undesirable quality discolorations, but even more disadvantageousis the pronounced loss of process effectiveness at high temperatures.

Another method relies on the use of atmospheric oxygen but this also hassimilar drawbacks, i.e., high temperatures are required. Hightemperatures result in considerably reduced product output.

It has been discovered and forms one of the major features of thisinvention that many polymers, particularly polyolefins, especiallypolypropylene, polybutylene and to some extent polyethylene (except whenthere are extensive accompanying cross-linking reactions), can be verysuitably narrowed in their molecular weight distribution by the use ofthe controlled process features wherein very excellent mixing ordispersion of reactants is accomplished by using a process employing oneof the extruder configurations as described herein.

When the polymer is in the molten state, at the proper temperature andat essentially reduced pressures with respect to a first stage meteringsection ofthe extruder or in a high shear-thin film mode (with highpressures), initiators of various types can be included with it, andvery rapid diffusion or dispersion of the initiator or other reactantthroughout the polymer will occur. Thus, it is possible to achieveextensive reactions with very short reaction zone residence times.

Directionally, in most instances, due to controlled degradation thelength of the individual polymer molecules will all tend to becomeapproximately the same, thus resulting in the desirable narrow molecularweight distribution as well as some concomitant reduction in molecularweights. Crystallinity and other desirable characteristics of thepolymer are retained.

Moreover, in place of or to supplement the molecular weight distributionalteration described above, reactive and/or polymerizable monomers canbe introduced in the presence of appropriate catalysts or initiators(usually the same compounds which cause polymer breakdown) with themonomer to cause grafting and usually, but not always polymerization ofsuch monomers on the active sites created in the polymer by theparticular reactive conditions existing in the zone at that time.

The process of the invention is particularly noteworthy since itprovides for the first time a technique for simultaneously narrowing themolecular weight distribution as evidenced by lower die swell of apolymer or making the polymer substantially more flowable, while at thesame time achieving a degree of grafting over a wide range.

Furthermore, a great many of the resulting grafted polymers with theirunique properties are also novel compounds. For instance, graftedpolypropylene with from 0.02 to 20 weight percent grafted componenthaving a MFR of fromabout 3 to 1,000, and preferably more than 20 to1,000, said MFR being at least 50/1 higher than the MFR of a basepolymer and with die swells at least 0.05 units lower than the basepolymer have never been prepared before.

ln this connection, it is important to grasp that two polymers withidentical MFR can be completely different in molecular weightdistribution, although roughly equal in viscosity average molecularweight. Thus, MFR is an approximate indication of viscosity averagemolecular weight. Die swell is a measure of molecular weightditribution. Generally, the lower the die swell, the narrower themolecular weight distribution. The latter is controlling for mostpractical purposes.

Grafted polymers with relatively narrow molecular weight distributionsare novel and preferred. The term relatively refers to the base polymerwhich is the polymer directly from synthesis, i.e., before anymeasurable scission, degradation, chain breakage, etc.

For most C to C polyolcfins, cross-linking is not a problem. But forthose that contain ethylene or for polyethylene, slightly differentprocedures can be effected to prevent cross-linking. Among these areincluded the creation of activated sites on the polyethylene byinitiators which do not promote crosslinking, e.g., gaseous oxygen,organic tin compounds, organic sulfur compounds, heat stabilizers,acidanhydrides and the like.

Also, either the initiators or monomers can be separately introduced ata time prior to the introduction of.

the other component, monomer, or initiator, so that the reaction tendsto form. grafts rather than to form crosslinks. Furthermore, thetemperatures can be controlled to minimize cross-linking.

The process of the invention is highly flexible and a great manymodifications such as those proposed above are available to carry outany particular purposes desired.

For instance, if the quantity of homopolymer formed by thepolymerization of the grafting monomer is desired to be decreased, it iscontemplated that initiator can be added to the polymer prior to theaddition of monomer (just a few microseconds prior is probably adequate)so that intimate mixing of the initiator with the polymer takes placeprior to the introduction of monomer. Thus, when the monomer isintroduced, large quantities of monomer do not contact large quantitiesof initiator, and the formation of homopolymer is minimized. The reverseof this process sequence could also be effected.

Of course, mixtures of monomer can be also added so as to achieve graftcopolymers in which the graft chains have at least two differentmonomers therein (in addition to the base polymer monomers).

It is also possible to graft materials to the polymers which do not formpolymers. For instance, it is possible to graft materials which couldact as antistats, light stabilizers, photodegradation agents, nucleatingagents, flame retardancy, heat stabilizers, plasticizers, slip agents,colorants, etc. One way of accomplishing this is by providing anunsaturated site accompanied by steric hindrance or bulkiness factors inthe monomer itself so that only one monomer grafts on to any one site.Thus,

polymerization is discouraged. Monomers that will react directly withthe functional grafts will also satisfactorily perform the abovefunctions.

The class of preferred monomers which will form graft polymers in theprocess of the invention have functional groups such as carboxylic acidgroups, hydroxy groups, nitrile, amine ester, polyether sequence groups,imide groups, amide groups, glycidyl groups, epoxy groups and the likein addition to at least one point of unsaturation.

These functionalities can be subsequently reacted in the extruder orlater with other modifying materials in order to change the propertiesof the graft and result in heat stabilizers, light stabilizers orabsorbers, nucleat ing agents, slip agents, photodegradation agents,flame retardancy, antistats, or plasticizers, etc.

For instance, a graft of an acid-containing monomer could be suitablymodified by esterifying the resulting acid groups in the graft withappropriate reaction with hydroxy-containing compounds or varying carbonatom lengths. The reaction could take place simultaneously with thegrafting or in a subsequent post modification reaction.

It is to be noted that the process of the invention differs considerablyfrom just a high shear process such as the one described in British Pat.No. l,042,l78. There, the speed of the extruder is extremely high andproduces exceptionally strong shearing activity. These shearing actionswork the polymer, melt it and cause degradation very shortly afterstart-up. They also would wear out the screw or blades in just a veryfew weeks.

Although this mode might be satisfactory for some purposes, it is to beappreciated that operation of equipment of this nature requires theinput of extremely high energy levels and therefore, is economically notattractive. Particularly, when compared to a process which usesrelatively low energy levels in terms of shear, that is, ordinaryextruder screw speeds. Thus, the process of the present invention usesrelatively low shear gradients in combination with initiators which areadded at very critical reaction zone points in the extruder operation.

Another advantage for the process of the invention and the products madetherefrom is that the resulting materials can be blended in essentiallyall portions with materials which have not been modifield. Relativelyhigh ratios of unmodified materials to modified materials can be used tocreate blends which partake of much of the improved properties of themodified polymer. Thus, the products of the invention have utility asadditives per se.

The grafted polymer will usually contain from 0.02 to 20, preferably 0.1to l0, and most preferably 0.2 to 8 weight percent of grafted portion.

When suitable monomers are used to form grafts, one of the outstandingproperties obtained in addition to the rheological flow properties whichhave been discussed above are very beneficial improvements in theadhesion properties of the polymer. Thus the grafted polymers of theinvention can be prepared to adhere to almost any substrate, even withrelatively low graft component, i.e., 1% or less graft based on totalpolymer. Many nonpolar polymers such as polyolefins do not adhere verywell to metal materials and other materials such as plastics, such asnylon, polyesters, fluoronated polymers, etc. Moreover, they do notaccept dyes, paints, coatings, metal plating, printing and the likewell, at all. After having been modified with the appropriate monomers,according to the process of the invention, modified polyolefins canpossess all of these attributes, which are lacking from thecharacteristics of the base polymer.

Furthermore, the materials, as modified, can still be used for anypurpose for which an unmodified material (base polymer) was formerlyused. That is, they can be foamed, formed into plastisols, powders,dispersed as colloidal mixtures, emulsified, extruded and molded in anyconvenient manner.

The preferred modifying monomers are unsaturated monoandpolycarboxylic-containing acids (C -,C,,,) with preferably at least oneolefinic unsaturation, and anhydrides, salts, esters, ethers, amides,nitriles, thiols, thioacids, glycidyl, cyano, hydroxy, glycol, and othersubstituted derivatives from said acids.

Examples of such acids, anhydrides and derivatives thereof includemaleic acid, fumaric acid, himic acid, itaconic acid, citraconic acid,acrylic acid, glycidyl acrylate, cyanoacrylates, hydroxy C,C 0 alkylmethacrylates, acrylic polyethers, acrylic anhydride, methacrylic acid,crotonic acid, isocrotonic acid, mesaconic acid, angelic acid, maleicanhydride, itaconic anhydride, citraconic anhydride, himic anhydride,acrylonitrile. methacrylonitrile, sodium acrylate, calcium acrylate, andmagnesium acrylate.

Other monomers which can be used either by them selves or in combinationwith one or more of the carboxylic acids or derivatives thereof include-C vinyl monomers such as acrylamide, acrylonitrile and monovinylaromatic compounds, i.e., styrene, chlorostyrenes, bromostyrenes,a-methyl styrene, vinyl pyridines and the like.

Other monomers which can be used are C, to C vinyl esters, vinyl ethersand allyl esters, such as vinyl butyrate, vinyl laurate, vinyl stearate,vinyl adipate and the like, and monomers having two or more vinylgroups, such as divinyl benzene, ethylene dimethacrylate, triallylphosphite, dialkylcyanurate and triallyl cyanurate.

Thus, in general, any material having the ability to react with the basepolymer, particularly under free radical conditions, and at the melttemperature of the base polymer is operable for the purposes of theinvention.

A large proportion of the materials falling in this class will bepolymerizable monomers, but not all. Some will be materials which arereactive with the base polymer, but do not form polymers, i.e., maleicanhydride.

Also, a large proportion ofthe materials falling in the class will havefunctionality in addition to unsaturation, but not necessarily so, i.e.,styrene or ethylene.

A subgeneric definition that encompasses a class of suitable reactantsis as follows:

b. when R, and R are H, R;, is H, halogen or C, to

C,,, alkyl and R is halogen,

O COOR5, Ro O-,

C to C preferably C to and most prefeibly C, to C alkyl, aryl, alkyaryl,and substituted derivatives thereof,

0 l CN, 0II, COOM, 3-01, -OHO SOC H,=,, SO C H wherein R H or R and R isa C to C hydrocarbon group and M is a metal of any valance.

c. R and R are H and R and R are connected into a strained ring compoundhaving 4 to 50 carbon atoms such as himic acid, vinylene carbonate,norbornenes, cyclopentadienes, cyclopentenes, cyclohexenes and the like.lt has been further noted that when grafts are produced in polymersaccording to the process of the invention that these grafted polymerswhen used in fairly small quantities act as nucleating agents, thus,accelerating or shortening the time period in which the polymer startshardening and forming solid plastic from the melt. They also tend toincrease the clarity of the polymer and therefore can be used forpurposes where clarity is important, e.g., films, bottles and the like.The nucleating effect can be observed at very low concentrations ofgraft polymer used as an additive in other polymers.

Of course, any of the standard additives can be used with these modifiedpolymers. They include conventional heat stabilizers, slip-agents,antioxidants, antistatic agents, colorants, flame retardants, heatstabilizers, plasticizers, preservatives, processing aids and the like.

Fibrous reinforcements such as asbestos, boron filaments, carbon andgraphite fibers, ceramic fibers, fibrous glass, fibers of other polymerssuch as polyvinyl alcohol fibers, sapphire filaments and whiskers;nonfibrous fillers such as barium sulphate, portland cement, talc fumedcolloidal silica, calcium carbonate, silica, metal powders, metallicoxides (interact with carboxyl groups), calcium silicate, glass spheres,Saran spheres, Kaolin clay, Nepheline syenite and the like. Ferrous andnon-ferrous wires and the like are particularly effective in thepolymers prepared according to the invention. The fillers orreinforcement materials can be added as they would to unmodifiedmaterials, or they can be added in many cases to the same extruder inwhich the modifying reaction is taking place.

The uses for the grafted polymers of the invention are vastly expandedin scope since good bonding and fastening are obtained with thesematerials. They can be printed and decorated through decorativeoverlays, electroplated, hotstamped, painted, printed and vacuummetalized.

Tapes made from the polymers of the invention, particularly those ofacrylic acid grafted polypropylene, are outstanding for adhering nailsin nail stacks to be used in nail guns.

The tapes are also outstanding for strapping and other uses whereadhesion and strength are important properties, especially whencontaining 10 to weight percent elastomer.

ln processing, they can be blow-molded by extrusion injection orpreformed, calender casting, centrifugally molded, extrusion coated,powder coated, transfer coated, compression molded, extruded, foamprocessed, injection molded, mechanically formed, rotationally molded,reinforced molded, thermoformed, web impregnated and the like. Thepolymers of the invention are especially suitable as coatings or filmlaminates to other polymers, e.g., laminates of glycidyl acrylategrafted polypropylene to nylon, Mylar, etc.

lt is to be emphasized that in the definition of the base polymer,substituted polymers are also included; thus, the backbone of thepolymer before grafting can be substituted with functional groups suchas chlorine, hydroxy, carboxy, nitrile, ester, amine and the like.

Furthermore, polymers which have been grafted with monomeric substances,particularly those with functional carboxylic acid groups, can beadditionally crosslinked in a conventional manner or by using metallicsalts to obtain ionomeric cross-linking.

It is very desirable to have a material which initially will flow veryreadily upon processing and will subsequently set up very rigidly, whenprocessing is finished, through cross-links. The materials produced bythe process of the invention are capable of being employed in thismanner. When cross-linking is contemplated, the polymer can be verydrastically decreased in molecular weight by using much more freeradical initiator, i.e., from 0.05 to 5 weight percent, based onstarting polymer. Polymers having intrinsic viscosities of 0.8 andbelow, i.e., 500 to 6,000, preferably 1,000 to 5,000, and mostpreferably 2,500 to 4,500 centipoises, are especially suitable forcross-linking after grafting with monomers described herein.

Not only can these low molecular weight polymers be cross-linked, butthey can also be emulsified and otherwise used for surface coatings.

Thus, it is within the scope of the invention that polymers can betreated with the process of the invention, not only in order to reducethe molecular weight and narrow the molecular weight distribution, fortradi tional plastic end uses, but also to make the polymer suitable foruse for surface coatings and adding to fuels, lubricating oils,lubricants and spray oils as viscosity modifiers, sludge inhibitors, andantioxidants.

Thus, for example, a-olefins, such as ethylenepropylene copolymers whoseviscosities have been reduced to a certain level and whose molecularweight distribution is narrow will exert excellent additive propertiesin lubricating oils over a wide range of temperatures.

The modified polymers of the invention are excellent blending agents.They impart unusual properties to other polymers even in small amounts,even when the other polymers have a considerably different MFR than themodified blending polymer. Generally, the polymers of the invention canbe beneficially blended with other polyolefins, i.e., thermoplastics andelastomers in quantities of 0.001 to 99, preferably 0.01 to and mostpreferably 0.01 to 10 weight percent based on the weight of theresulting blend.

in an especially preferred embodiment, the process of the presentinvention is directed to grafting a poly mer of a C to C mono-a-olefinor its copolymers with acrylic acid. The polymers of C to Cmono-a-ololefins are referred to as polyolefins and for the purposeofthis invention are to include copolymers of the C to C mono-a-olefinswith each other and with other monomers as well as the homopolymers.

Polymers containing diolefms such as butadiene and isoprene are alsosuitable. The polyolefins are produced, utilizing in most instances atransition metaltype catalyst, but can also be Phillips-type catalysts,cationic or anionic-type initiators and high pressure free radicaltechnology. The processes for making the C to C polyolefins are wellknown and form no part of the present invention.

Examples of suitable polyolefins, both plastic and elastomeric, includelow or high density polyethylene, polypropylene, polybutene-l,poly-3-methylbutene-l, poly-4-methylpentene-l, copolymers of monoolefinswith other olefins (monoor diolefins) or vinyl monomers such asethylene-propylene copolymers or with one or more additional monomers,i.e., EPDM, ethylene/butylene copolymer, ethylene/vinyl acetatecopolymer, ethylene/ethyl acrylate copolymer,propylene/4-methylpentene-l copolymer and the like.

The term copolymer includes two or more monomer constituents andsubstituted derivatives thereof.

The preferred polyolefins employed in the present invention containpropylene and/or ethylene, i.e., polypropylene and polyethylene. Thestarting polymer used as a base material in the present invention willpreferably have a melt index (Ml) of 0.05 to 1000, preferably 0.5 to 50,and most preferably 005 to 10, or melt flow rate (MFR) between about 0.1to 50 and preferably 0.1 to 5.0, most preferably 0.5 to 2.

In the preparation of normally solid polymers of lolefins, certainrheological properties are frequently utilized for control purposes. Oneof these rheological properties more usually employed is melt index ormelt flow rate which characterizes the processability of the polymersand is also an approximate indication of polymer molecular weight.

The melt index of polyethylene is measured normally according to theASTM text D-l238-65T. In this test the rate of extrusion in grams per 10minutes (through an orifice 0.0825 inch in diameter and 0.315 inch inlength) is determined for the polymer at 190 C. under the weight of apiston having a diameter of 0.373 inch and weighing in combination withits plunger 2160 grams.

The melt flow rate (MFR) of polypropylene is determined by the sameprocedure except at a temperature of 230 C. according to ASTMD-1238-65T.

The apparatus utilized for determining melt index is defined in ASTMmanual as a deadweight piston plastometer."

Generally speaking, polypropylene from a reactor will have MFR below 1,while polyethylenes from a reactor can have a Ml of about 0.05 to 50 Thepreferred monomers to be grafted to the C to C,, polyolefin and otherpolymers according to the present invention are maleic anhydride,acrylic acid. methacrylic acid, glycidyl acrylate, acrylamide, hydroxy Cto C alkyl methacrylates and their derivatives. Others that can be usedare described elsewhere herein. However, other monomers may be added inadmixture with these such as maleic anhydride (MA), styrene, acidesters, salts and the like to form graft copolymers. MA and styrene andMA and acrylic acid are preferred over MA alone when polymer grafts ofMA are desired.

The grafting reaction is initiated by a free-radical initiator which ispreferably an organic peroxygen compound. Especially preferred peroxidesare t-butyl perbenzoate, dicumyl peroxide,2.5-dimethyl2,S-di-tertbutylperoxy-3-hexyne (Lupersol 130),a,a-bis(tertbutylperoxy)diisopropyl benzene (VulCup R), or any freeradical initiator having a 10-hour half-life temperature over C. ormixtures thereof. Generally, the higher the decomposition temperature ofthe peroxygen compound, the better. See pp 66-67 of Modern Plastics,November 1971, which is incorporated hereby by reference, for a morecomplete list of such compounds.

An Illustrative Embodiment Referring to FIG. 1, an extruder 1, having afeed zone 2, a reaction zone or chamber 3, and a final metering zone 4is utilized to carry out a preferred embodiment of the grafting processof the present invention.

In effect, polypropylene of a predominantly isotactic crystalline natureis introduced into a hopper 5 in the feed zone 2 of the extruder 1. Theextruder screw 6 in feed zone 2 can be of various conventional designssuch as a feed portion 7, a transition portion 8 and a first stagemetering portion 9.

In feed zone 2, the polypropylene is heated by heaters 10 to a barreltemperature in the range of 400 to 650 F., preferably 400 to 550 F. Itis one of the advantages of this invention that fairly low temperaturescan be used to accomplish outstanding modification. ln processesutilizing 0 as an initiator, much higher barrel temperatures, i.e.,about 600 to 800 F. are re quired and control is awkward. 1n processesutilizing heat alone, even higher temperatures and reaction times arenecessary.

Extruder screw 6 has a root (sometimes called core) starting at theinitial boundary of reaction zone 3 with a reduced cross-sectional area11. This provides additional volume for reaction zone 3. When polymerunder pressure reaches zone 3a, the increased available volume resultsin a pressure drop, i.e., decompression, so that particular mass ofpolymer is not subjected to the ordinarily high pressures in theextruder.

An injection line 12 connects reaction zone 3 to a source of initiator,preferably a peroxide. In some instances the peroxide will be combinedwith a active monomer. For the purposes of this specific embodiment, themonomer is acrylic acid and the initiator is VulCup R.

injection of initiator or initiator and monomer at this point, where lowpressures in zone 3a prevail, provides thorough dispersion of theinitiator in polypropylene over an extremely short period of time andappreciable scission or degradation of the polypropylene results.Appropriate controls of the polypropylene feed rate and screw speeds aremaintained.

The process of the invention can be conveniently operated to give highthroughputs with good quality. In this particularly preferredembodiment, the initiator and acrylic acid are added as a liquid blendto zone 3. When only degradation is desired, initiator alone orinitiator dissolved in a solvent is introduced into zone 3.

It has been found that appreciable degradation of the polypropyleneoccurs when the back pressure against the liquid mixture of initiatorand acrylic acid in injection line 12 is less than about I psig,preferably about 0 psig.

The pressure in injection line 12, therefore, provides one indicia thatthe polypropylene feed rate and screw speed are being appropriatelycontrolled for the particular products desired.

The resulting graft copolymers of the present invention have beenappreciably degraded and changed in molecular weight distribution ascompared to the base polymer. This is demonstrated by the fact that thegraft copolyme rs of the invention have a lower die swell than thepolypropylene base stock used in making the copolymer. Lower molecularweights are also indicated by changes in melt flow rates.

The portion of the extruder heated by heaters 13 will have a temperatureof from about 160 to 450 F., preferably 250 to 450 F. The importantthing is that the polymer be substantially in a melt phase during thereaction. The extruder screw 6 in the latter portion of reaction zone 3can have any desired root cross-sectional area desirable to provide forpumping and ancillary mixing if desired and to allow residual reactantsto complete their reaction.

It is to be noted that some homopolymerization of the acrylic acid (orany other monomer) to form polyacrylic acid also occurs. But thisusually does not exceed 30% of the total acrylic polymer formed,particularly at the low monomer concentrations.

Preferably, the decompression portion 3a of the screw is immediatelyfollowed with transition zone 3b of gradually increasing screw rootcross-sectional area followed by a metering zone 3c of constantcrosssectional screw root area.

Thereafter, extruder screw 6 has a melt seal (also called cap orblister) 14 which prevents the free escape of initiator and acrylic acidfrom reaction zone 3.

Screw 6 also has a second decompression portion 15 following blister l4.

Vent line 16 (which can be optionally provided with vacuum, if desired)is positioned above decompression portion 15 to remove gases or vapors.When operating without vent line 16, blister 14 and decompression zone15 may be omitted.

The graft copolymer and homopolymer blend is then passed throughmetering zone 4 where it is extruded from a die 17 at the end ofextruder 1.

The extruder barrel temperature heated by heaters 18 in metering zone 4is in the range of 350 to 550 F., preferably 350 to 450 F.

Referring now to FIG. 2, extruder 20, having a feed zone 21, a reactionzone 22 and a final metering zone 23, is also utilized to carry out thegrafting process of the present invention. The process is generallysimilar to that described above for FIG. 1, except as follows. In onepreferred embodiment, the initiator and acrylic acid are injectedthrough injection port 24 at a point where the extruder screw 25 has aroot 26 of very large cross-sectional diameter. The clearance betweenthis portion of the root and the interior of extruder 20 is very smalland will vary with extruder size. For example, in a 2-inch extruderapparatus this'clearance is from 5 to 50, preferably 10 to 25, and mostpreferably 10 to 20 mils. I

In another preferred embodiment shown in FIG. 3, the root of increasedcross section or mixing device 26 is shown with a series of channels cutin the perimeter of the device. This results in a series of dead endchannels. Under pressure, this forces the polymer out of the inletchannels and across the outer surface to the outlet channel. Othersuitable devices could be used.

The novelty and unobviousness of the invention'reside in the combinationof such a mixing device with means to introduce reactants at arelatively early stage in the extrusion process.

In any event, whether the embodiment of FIG. 2 or FIG. 3 is used, thepolymer forms a thin fluid film under relatively high shear as comparedto the other portions of the extruder.

The initiator and/or acrylic acid are injected at pressures which rangebetween 200 and 5,000 psi or more specifically, between 500 and 3,500psi. At these high pressures and because only a thin film ofpolypropylene is present at the high shearthin film zone 27 of reactionzone 22, intensive, instantaneous mixing followed by appreciabledegradation of the polymer, e.g., polypropylene, occurs.

Extruder 20 is also provided with a blister 29 and a vent 30. As in thecase of the FIG. 1 extruder, the vent, decompression zone, and blistermay be eliminated if desired.

As illustrated by the two embodiments of FIG. 1 and FIG. 2, variousextruder designs may be employed to carry out the graft copolymerizationprocess of the present invention. However, the common characteristic ofeach extruder design is that thorough, instantaneous mixing of theinitiator and acrylic acid with the polymer, i.e., polypropylene,occurs. The extremely high degree of mixing which characterizes theprocess of the present invention is evidenced by appreciable degradationof the polymer. Evidence for the appreciable degradation of thepolyolefin is shown by the sub stantial increase in the melt flow rateor melt index of the copolymer over the base resin. Evidence for anarrowing of the molecular weight distribution is seen from the factthat the die swell of the graft copolymer is lower than the die swell ofthe polyolefin base stock used in making the copolymer. It is to beemphasized that a change in molecular weight distribution leads to manyuseful and novel properties of the resulting polymers.

Die Swell Some high molecular weight polymers such as polyolefins whenforced through a capillary die of a relatively short length produce anextrudate of a larger diameter than the diameter of the capillary.

This property of polymers has been characterized as die swell which isexpressed numerically as the ratio of the diameter of the extrudate tothe diameter of the capillary (by some the ratio to the first power andby others to the second power). The term die swell as used herein isdefined as follows:

die swell (D /Dul where: D, is the extrudate diameter D is the capillarydiameter.

The numerical value of die swell is also dependent on the geometry ofthe rheometer used to force the polymer through the capillary. 1nobtaining the numerical values set forth herein, and in the tables whichfollow, a rheometer having a rheometer barrel of /8 inch l.D. (insidediameter) was used wherein the barrel was heated to a temperaturecontrolled to t2 F. of the recorded temperature and the polymer wasforced through a capillary having a 0.03018 inch 1D. and which was 1.006inch long. The capillary had a 90entry angle.

The measurements were made by forcing the polymer through the capillaryby a plunger operating at a constant speed or a constant shear rate (y)ranging from 13.5 reciprocal seconds to 338.3 reciprocal seconds (sec'lThe polymer was forced through the capillary into ambient air at roomtemperature (70 80 F.).

The measurement of die swell is frequently used as a gross measure ofmolecular weight distribution in polyolefins; high die swell resinspossess broader molecular weight distribution than polymers having lowerdie swells.

Thus, the polymers of the invention have die swells lower than the basestock from which they were prepared, are the product of a random chainscission process, which results in molecular weight degradation andhence possess narrower molecular weight distribution than the basepolymers.

It should be noted that the exceptionally high MFR grafted polymers(i.e., those having a MFR of about to 1,000) can also be made byutilizing a starting polymer having a MFR in that range andconventionally grafting and/or additively degrading.

Films and coatings made from the grafted polymers or laminated or coatedon other films or structures made from polar monomers, show outstandingproperties. Nylon and other polar materials can be used as a basestructure.

To summarize, the graft copolymers of the present invention haveoutstanding utility due to their unique chemical and physical propertiesas bonding agents, adhesives and coatings. The graft copolymers areespecially good as adhesives for metals and can be used in forms such asadhesive sheets, powders, tapes, or laminated products. They can beadded to conventional adhesive compositions.

Still further, the mechanical properties of the grafted polymer,preferably polypropylene, may be enhanced by incorporating with thecopolymer certain fillers to dramatically increase the bonding abilityof the conventional adhesive.

For example, a polypropylene grafted with 6% acrylic acid was found tohave aluminum to aluminum shear adhesion of about 1,200 psi at 72 F. andin excess of 250 psi at 250 F. These fillers are preferably asbestostalc and fiber glass, and of the types of asbestos, chrysotile asbestosis preferred. The filled acrylic acid grafted polyolefin may beinjection molded into objects such as kick-panels for automobiles,washing machine tubs or other uses where enhanced mechanical propertiesare required.

The polymers of the invention are also very useful in powdered form,i.e., from 20 to 325 mesh or smaller.

The graft copolymers of this invention also have outstanding utility ascoupling agents. Thus they can be coated in thin films on variousfillers such as glass fibers which are subsequently dispersed in apolymer matrix, which polymer can be selected from a wide availablevariety.

An especially useful post-modification or simultaneous reaction with anacid grafted polymer is to improve the UV stability in either of twoways or a combination of the two. They are:

a. Nickel-containing basic salts, e.g., nickel oxide, nickel hydroxide,etc., are reacted with the acid groups in the polymer; and

b. The hydroxy functionality of a hydroxy benzophenone is reacted withthe acid groups of the polymer.

In addition, conventional stabilizers are much more compatible with acidmodified polyolefins, and the product of the invention can be used tomasterbatch stabilizer or other additives which are not normallycompatible with polyolefins.

For instance, a typical masterbatch will have from 10 to 70, preferably10 to 50 and most preferably 10 to 30, weight percent additive and thebalance is acidmodified polymer.

It will be understood that while the modified polymers of the inventionare especially suitable for many of the end use applications discussedherein, grafted polymers prepared by processes known to the art willalso be useful in many of these end uses.

The acid grafts of the invention can be used as polymerizationinitiators for ethers, esters, polyethers, polyamides, etc. They canalso serve as initiators and growth sites for ring opening reactionssuch those utilizing caprolactam.

Thus many end uses, post-modifications, etc, disclosed herein have neverbeen previously described or available to the art. Thus, these processesfor modifying and using graft polymers are novel and unobvious in theirown right.

General Reaction Conditions The free radical initiator is used inamounts corresponding to 0.005 to 5, preferably 0.02 to 2, mostpreferably 0.02 to 1.0 weight percent based on polymer.

The monomer to be graft polymerized is used in amounts of 0.01 to 100,preferably 0.05 to 50, and most preferably 0.1 to 25 weight percent ofthe base polymer. An especially preferred range is from 0.1 to 1.5. Highgraft conversions are obtained at these levels. Furthermore, adhesionproperties are also greatly enhanced over the base polymer, even withsuch low quantities of graft.

Generally, the monomer and initiator are blended together and addedsimultaneously, except in the situation of a polyethylene or ethylenepredominant copolymer.

Characteristics of Inventive Polymer The novel graft polymers of theinvention are characterized by several important properties. These are:

1. A MFR of from 3 to 1,000, preferably 11 to 250, most preferably 21 toand at least 50% or more, preferably 100% or more, and most preferablyat least or more higher than the MFR of a starting polymer having a MFRof from no-flow to 150 as measured under conditions of ASTM test No.D-1238-65T.

2. A polymerized graft comonomer content of from 0.02 to 20, preferably0.1 to 10, and most preferably 0.2 to 8, based on the total weight ofthe graft copolymer. (In this connection, it has been noted that thebeneficial effects of the graft are noted at Continued relatively lowgrafted comonomer contents, i.e., Tm lAgr li Add i r H3 r,

Product, wt. /1 1% f less') '7: Conversion of Acrylic Acid 83 87 89 903. A die swell at least 0.05, preferably at least 0.1 and n hmssqrcAgnins! 150 -41) 150 300 most preferably 0.15 of a unit less than thatof the base polymer.

The pre sem mvfmuon Wm be further Husmned by It has been observed thatwhen the graft monomer is the fonnwmg Speclfic examples incorporated tobe about 5 wt. or less of the total pl 1 m graft polymer, graftconversions are relatively high. At A Senes of composltlons wereprepared 1 lmroduc' about to wt. "/1. of the total graft, conversionsare mg polypropylene having a MFR of 0.4 mto the exlower Lew to truderof 1 thr9ugh hopper Int) mlectloll me As can be seen from the abovetables, the acrylic acid conflectd to a slde port was mtroduced mlxnfrepercentage of the copolymer is related to the injection of acrylic acidand a peroxide (VulCup R) in the ra rate. Total conversion of acrylicacid to polymer is relaas set forth in Table 1 which follows. Forcompositions tively high under both Sets f conditions- A-G, inclusive,the acrylic acid and peroxide were E n 3 added with essentially no backpressure on the injec- Th compositions f E l 1 were evaluated. line 12,which was located Over the decompression The thorough dispersion andmixing of the initiator portion of the screw. 20 with the resultingappreciable degradation of the poly- FOI' compositions 1'1-K, incontrast, the acrylic acid propylene for compositions A-G is clearlyapparent in and peroxide were added to a standard extruder under thelower die swell and higher melt flow rate data obconditions where thereaction zone was filled with polytained for these to the base polymer.mer and considerable melt pressure was evident against in contrast, thepolypropylene acrylic acid graft cothe injection line. The conditionsunder which the graft 25 polymers of compositions H-K have die swellseither copolymerizations were carried out are fully set forth the sameor higher than the polypropylene base stock in Tables 1 and 11 asfollows: and suffered very little molecular weight loss. This TABLE I(No Pressure Condition) Composition A B D E F G Barrel Temperatures FeedZone, F. 520 520 520 520 520 520 520 -490 490 490 -490 490 -490 -490Reactor Zone. F. 305 320 305 305 295 305 305 400 -400 400 400 -400 400400 Metering Zone, F. 450 450 450 450 450 450 450 400 -400 -400 -400-400 -400 -400 Output, lb/hr 92 99 95 -90 9O Screw Speed, RPM 160 160160 160 160 160 160 gr Peroxide/ gr Acrylic 15 15 15 15 30-35 15 15 AcidAcrylic Acid Injection Rate, 3.26 6.22 6.46 6.30 6.35 -8.9 9.92 wt.Total Acrylic Acid in 2.66 5.85 5.58 5.29 6.03 -7.5 8.60 Product, wt.Conversion of Acrylic Acid 81 94 86 84 95 -85 87 Melt Pressure Against 00 0 0 O 0 0 Injection Line, psi

TABLE 11 clearly indicates no appreciable degradation of thecompositions H-K during the grafting of the acrylic (Full PressureCondition) I Composition H J K AC1 I I Furthermore, the increase in MFRof the graft co- 311ml Tcmpflfllurcs 5O polymers in compositions A-Gover the MFR of the .n 1 7 2738 358 jig base resin shows thatappreciable degradation occurred Reactor Zone, F. 300 300 300 208 incontrast to the slight increase in MFR of the graft co- -400 -400 400 1Mcming Znmsp 450 450 450 450 polymers of compositions H K over the MFRof the 400 400 -400 400 base resin. g p b RPM 28 25 28 2 55 The dieswell data and melt flow rate data are sumfi'tf l jg g gr Acrync 15 1515 I5 marized as follows in Tables 111 and 1V. (Acrylic acid Acid Igraft contents have been rounded off to the closest clcrahc Acld inection Rate. 3.84 6.71) 7.83 9.96 Whole number) TABLE III CompositionBase A B C D E F G Stock MFR 0.4 6.5 11.2 10.6 10.2 49.7 11,4 13.3 Wt.Acrylic Acid 0 3 6 6 6 6 9 (Approximate) Die Swell at 400F.

-9= 13.5 sec" 1.67 1.35 1.35 1.35 1.42 1.50 1.35 1.20 i 33.8 sec" 1.761.35 1.35 1.35 1.42 1.50 1.35 1.27 7" 67.7 sec 1.85 1.42 1.35 1.35 1.421.50 1.35 1.42 9 135.3 sec 1.94 1.50 1.42 1.35 1.42 1.50 1.50 1.42 9338.3 sec 2.53 1.67 1.76 1.59 1.59 1.85

19 20 TABLE [V Example 5 The procedure for composition A of Example 1was Composition H l J K essentially dupliciated except that glycidylacrylate was MFR H 09 08 I7 substituted for acrylic acid. The resultantmodified W147, Acrylic Acid 5 graft copolymer exhibited unusually highadhesion to (Approximate) aluminum foil, polyester (Mylar) and nylonfilm when i fg ig fr L67 "67 L67 1 76 compression molded at 450 F. Theresults are summai gg sec: .3 19424 rized below in Table VII.

;= 1353 220 2122 2.32 2.32 5.75 TABLE 9 338.3 sec" 2.53 2.64 2.75 3.32 l

Peel Strength lh/in Sample Al foil Mylar Example 4 Polypropylene U U Toillustrate the incorporation of fillers, particularlyPt)lypropylcnc-g-glycidyl acrylatc 12.0 hm strung Chrysotile asbestosand fibrous glass, and the enhanced 15 mechanical properties obtained,the polypropylene acrylic acid graft copolymer of composition E wasExample 6 compared with unmodified polypropylene homopoly- The generalprocedure of Example 1 was repeated mer used as a base which had a MFRof about five. The except that maleic anhydride was substituted formechanical properties of the polypropylene acrylic 20 acrylic acid andthat the maleic anhydride was added acid graft copolymers of the presentinvention are with the polypropylene and the initiator (dicumylpergreatly improved as compared to the properties of a oxide,shown asDCP,or LUPERSOL 130, shown as L) filled unmodified polypropylenehomopolymer. The was added in benzene or xylene solvent directly to theresults are summarized below in Tables V and V1. polymer melt.

TABLE V Secant Izod Impact ft Ib/ in TABLE VI Izod lmpact ft lb/inUnnotch Unnotch Unnotch 72F 0F 20F Notch Sample 72F Polypropylene 50%Chrysotile Asbesto Poly ropylene Gra ted with 6% Acrylic Acid 50%Chrysotile Asbestos Polypropylene 20% Fiberglass Polypropylene Graftedwith 9% Acrylic Acid 20% Fiberglass Hinged Composition G FlexuralTensile Unnotch Unnotch Unnotch Modulus Mpsi Heat Deflection Temperatureat Strength 264 psi C psl Secant Flex- Tensile Heat Deflection uralModulus Mpsi Strength psi Temperature at 264 psi "C The startingpolypropylene had a MFR of about 0.5.

A series of runs were carried out. The conditions and data on theresulting compositions are summarized below in Table V111.

TABLE VI II Maleic Anhydride Grafts Product Maleic Maleic Maleic Com-Peroxide Anhydride Anhydride Anhydride MFR p sition Solvent Atm DCPAdded Total Graft (230 C.

L Xylene Air 0.16 1.0 0.33 0.27 69 M Xylene N; 0.14 1.0 0.43 0 28 71 NBenzene Air 0.13 1.0 0.27 0 23 51 O Benzene Air 0.14 0 0 0 1 1.5 PBenzene N 0.14 1.0 0.28 0.23 46 Q Benzene Air 0 1.0 0.23 O 1.2 R BenzeneN 0 1.0 0.31 0 1.1 S Benzene N 0.0851. 1.0 0.38 0.24 60 T Benzene Air0.085L 1.0 0.33 0.21 56 U Benzene Air 0.23 3.0 0.58 0.42 56.9 V BenzeneAir 0.29 3.0 0.90 0.53 W Benzene Air 0.085L 3.0

X Benzene Air 0.044L 1.0 0.25 0.17 39.0 Y Benzene Air 0.084L 1.0 0.280.20 57.4 Z Benzene Air 0.089L 1.0 0.29 0.22 54.8 AA Benzene Air 0.052L1.0 0.33 0.17 24.3 BB Benzene Air 0.047L 3.0 0.33 0.20 262 CC BenzeneAir 0.094L 3.0 0.41 0.29 64.2 DD Benzene Air 0.088L 3.0 0.40 0.26 69.8EE Benzene Air 0.044L 3.0 0.35 0.20 35.9 FF Benzene Air 0.10L 0 37.9 G6Benzene Air 0.050L 0 135 HH Benzene Air 0.045L 0 17.6 11 Benzene Air0.087L 0 35.2 .1.1 Benzene Air 0.0491. 1.0 0.26 0.15 3 3 .0

As can be seen from the above table, grafts with good maleic anhydrideconversions as well as high melt flow rates can be conveniently preparedby the method of 35 the invention. Example 7 Composition V wasreinforced with an asbestos filler and compared in several importantproperties with the base polypropylene similarly reinforced. The resulare summarized below in Table 1X.

TABLE 1X less fiber attrition during compounding and molding of thecomposite due to the lower viscosity of the higher MFR material,resulting in longer length fibers. I

The modified materials of the invention also display low shrinkage andwarping characteristics upon in iec tion molding.

For the purposes of this application, the polymers included in the scopethereof include polystyrene and Secant Flexural Tensile Notch UnnotchUnnotch Unnotch Modulus Mpsi lzod Impact ft lb/in Heat DeflectionStrength Temperature at psi 264 psi C.

Polypropylene 35% Chrysotile Asbestos Maleic Anhydride GraftedPolypropylene 35% Chrysotile Asbestos As can be seen from the abovetable, improved stiffness, impact and tensile strength result, whileheatdeflections are comparable to the base polypropylene.

When talc or fibrous glass is substituted for the above filler, similarresults are observed.

It is also to be noted that in this connection generally from 100 to 5weight percent of grafted polymer will impart improved results. Thusconsiderable savings can often be effected by using less than 100% ofthe grafted resin batch.

It is further to be noted that higher MFR grafted polymers, i.e.. 50MFR. give directionally better comtetrahydro-Phthalic anhydride or acid.

The grafted polymers of the invention, particularly polyolefins and mostparticularly elastomer and plastic blends, are especially suitable forhot-melt adhesive constituents. Blends of acrylic acid graftedpolypropylene and EPR are particularly preferred.

The grafted polymers, especially acrylic acid grafted polypropylene, areexcellent additives to polyvinyl materials such as PVC as processingaids, i.e.. lubricants and heat stabilizers. About 1 to 20 weightpercent of a 6% acrylic acid graft makes an outstanding novel PVC blendcomposition.

The grafted polymers of the invention are also very compatible with dyesand carbon black. Therefore they propylene block polymer and 20 to 40weight percent of EPR or EPDM. From 0.5 to 15 weight percent of acrylicacid grafted to this blend is especially preferred.

Although unsaturated monomers are preferred, saturated carboxylic acid sc r be used to incorporate car boxyl functionality to the backbone of adegraded polymer.

A very important aspect of the invention which must be emphasized isthat in its preferred version simultaneous polymer degradation andgrafting are accomplished. This is an accomplishment unrealized by theart.

The especially preferred grafted polymer compositions of the inventionare characterized by the characare especially suitable as carryingmaterials for master l5 teristics in the following Tables A and B:

TABLE A Predominantly Ethylene-Containing Polymers Melt Index StartingFinal 0.05 to 1000 0.05 to 1000 0.05 to 50 0.05 to 250 to .05, pref. 0to 0.1, most pref. 0 to 0.15 O to .05, pref. O to 0.1, most pref. 0 to0.15

Die Swell Reduction at least: M1 Increase 1 to 10 l to 10 0 to .05,pref. 0 to 0.1, 0 to 20,000, pref. 0 to 1,000,

most pref. 0 to 0.15 most pref. 0 to 500 TABLE B Predominantly C to CContaining Polymers MFR Die Swell Reduction MFR Increase Starting Finalat least: at least:

0.3 to 0.9 3 to 1,000, 0.05, preferably 0.10, 1,000, preferably 1500,

pref. 3 to 300, most preferably 0.15 most preferably 2,000 mostpreferably 3 to 200 0.91 to 5.0 to 1,000, .05, preferably 0.10, 500,preferably 700, pref. 5 to 300, most preferably 0.15 most preferably 900most preferably 5 to 200 5.01 to 10 15.5 to 1,000, .05, preferably 0.10,300, preferably 400, pref. 20 to 300, most preferably 015 mostpreferably 750 most preferably 25 to 250 10.1 to 150 to 1,000, .05,preferably 0.10, 50, preferably 100,

pref. to 300,

most preferably .15 most preferably 150 most preferably to 250 batchesfor dyes, carbon black, other fillers, additives and the like.

, The process of the invention is particularly suitable for preparingblends of ordinarily hard to mix or incompatible components. Forinstance, blends of saran and polypropylene with good flame retardancyare made in the extruder process.

Another technique which can be used in an extruder process is to usepolypropylene and the like as a carrier for materials which aresometimes too slippery in fluid form for the extruder to handle, i.e.,low density polyethylene, EPR, etc.

Although the above examples were carried out with the apparatus of FIG.1, it is to be noted that the apparatus of FIGS. 2 and 3 has also beenused. In many instances, the results are even better than theoutstanding results obtained from the FIG. 1 apparatus.

In the above examples and specification, all weights are weight percentsunless otherwise indicated.

Another especially preferred composition to be grafted comprises 20 to60 weight percent polypropylene, 20 to weight percent polyethylene orethylene- What is claimed is:

1. A process for modifying the rheological or chemical and rheologicalproperties of a polymer which is normally solid at room temperature,which comprises in combination the steps of:

a. introducing said polymer into an extruder with a moving positivedisplacement screw of varying root cross-sectional areas to define areaction zone;

b. generating an above-atmospheric pressure within said extruder as saidpolymer is conveyed therethrough;

c. applying sufficient heat in addition to working said polymer, toconvert it into its fluid form;

d. conveying said fluid polymer to a reaction zone within said extruderwhere polymer volume is controlled to be less than said reaction zonevolume, thereby causing a reduced pressure within said zone;

e. introducing into said reduced pressure zone, while said polymer issubstantially fluid, sufficient of a material selected from the groupconsisting of i. one or more monomers;

ii. free-radical initiator;

iii. a combination of the foregoing; to measurably change either therheological or chemical propcities or both of said properties of saidpolymer; and

f. conveying the resultant modified polymerr through the remainder ofthe extrusion process.

2. A process according to claim 1 wherein said polymer is athermoplastic polymer.

3. A process according to claim 2 wherein said polymer is a C to Colefin polymer.

4. A process according to claim 3 wherein said polymer is either high orlow density polyethylene.

5. A process according to claim 3 wherein said polymer is polypropylene.

6. A process according to claim 3 wherein said polymer is chosen fromthe group consisting of polymethyl pentene, isotactic polypropylene,polyallomers, polybutylene and mixtures thereof.

7. A process according to claim 1 wherein said polymer is an elastomer.

8. A process according to claim 7 wherein said elastomer is anethylene-propylene copolymer or an ethylene-propylene diene terpolymer.

9. A process according to claim 1 wherein said monomer is unsaturatedand has carboxylic acid functionality or a derivative of said acidfunctionality.

10. A process according to claim 1 wherein said monomer is acrylic acidor one of its derivatives.

11. A process according to claim 1 wherein said monomer is maleicanhydride or one of its derivatives.

12. A process according to claim 9 wherein the modified polymerresulting from the process is subsequently modified by subsequentreactions chosen from the group consisting of esterification,neutralization, amidization and imidization.

13. A process according to claim 1 wherein said freeradical initiator isintroduced in the absence of freeradical reactive monomers.

14. A process according to claim 1 wherein said freeradical initiator isintroduced in the presence of freeradical ractive monomers.

15. A process according to claim 1 wherein the initial,

portion of said reaction zone is at a relatively low pressure ascompared to the rest of said reaction zone.

16. A process according to claim I wherein said polymer is a blend of aplastic and an elastomer.

17. A process according to claim 1 wherein said monomer is chosen fromthe group consisting of acrylic acid, glycidyl acrylate and maleicanhydride, and said polymer is polypropylene.

18. A process according to claim 1 wherein said monomer is chosen fromthe group consisting of acrylic acid, glycidyl acrylate and maleicanhydride, and said polymer is an ethylene-containing polymer.

19. A process for modifying the rheological or chemical-rheologicalproperties of a polymer which is normally solid at room temperature,which comprises in combination the steps of:

a. introducing said polymer into an extruder with a moving positivedisplacement screw. of varying root cross-sectional area to define areaction zone;

b. generating an above-atmospheric pressure within said extruder as saidpolymer is conveyed therethrough;

c. applying sufficient heat in addition to working said polymer, toconvert it into its fluid form;

d. conveying said fluid polymer through the initial portion of saidreaction zone whereby said fluid polymer is forced into a relativelythin, as compared to the portion of said extruder just prior to saidinitial portion of said reaction zone, fluid film under high shear;

e. introducing into said initial portion of said reaction zone whilesaid polymer is in a thin-film, high-shear state sufficient of amaterial selected from the group consisting of:

i. a monomer or monomers;

ii. a free-radical initiator;

iii. a combination of the foregoing; to measurably change either therheological or chemical properties or both of said properties; and

f. conveying the resultant modified polymer through the remainder of theextrusion process.

20. A method according to claim 19 wherein said initial portion of saidreaction zone is characterized by a relatively large screw rootcross-sectional area as compared to the screw root cross-sectional areaimmediately preceding said reaction zone.

21. A process according to claim 19 wherein said polymer is a C to C,,olefin polymer.

22. A process according to claim 21 wherein said polymer is either highor low density polyethylene.

23. A process according to claim 21 wherein said polymer ispolypropylene.

24. A process according to claim 21 wherein said polymer is chosen fromthe group consisting of polymethyl pentene, isotactic polypropylene,polyallomers. polybutylene and mixtures thereof.

25. A process according to claim 19 wherein said polymer is anelastomer.

26. A process according to claim 25 wherein said elastomer is anethylene-propylene copolymer or an ethylene-propylene diene terpolymer.

27. A process according to claim 19 wherein said monomer is unsaturatedand has carboxylic functionality or a derivative of said acidfunctionality.

28. A process according to claim 19 wherein said monomer is acrylic acidor one of its derivatives.

29. A process according to claim 19 wherein said monomer is glycidylacrylate or maleic anhydride or one of its derivatives.

30. A process according to claim 27 wherein the modified polymerresulting from the process is subsequently modified by subsequentreactions chosen from the group consisting of esterification,neutralization, amidization and imidization.

31. A process according to claim 19 wherein said free-radical initiatoris introduced in the absenceof free-radical reactive monomers.

32. A process according to claim 19 wherein said free-radical initiatoris introduced in the presence of free-radical reactive monomers.

33. A process according to claim 19 wherein said polymer is a blend of aplastic and an elastomer.

34. A process according'to claim 19 wherein said monomer is chosen fromthe group consisting of acrylic acid, glycidyl acrylate and maleicanhydride, and said polymer is polypropylene.

35. A process according to claim 19 wherein said monomer is chosen fromthe group consisting of acrylic acid. glycidyl acrylate and maleicanhydride, and said polymer is an ethylene-containing polymer.

36. A grafted polymeric composition, prepared from a base polymer,comprising from 0.02 to weight percent of grafted compound and having amelt flow rate of from 3 to 1,000 and at least 50% higher than said basepolymer and a die swell of at least 0.05 unit less than that of saidbase polymer wherein said grafted composition has been prepared by theprocess of claim 1.

37. A composition according to claim 36 wherein said base polymer ispolystyrene or a C to C polyolefin and said grafted portion of saidpolymer is derived from unsaturated carboxylic acids or theirderivatives.

38. A composition according to claim 36 wherein said base polymer isplastic.

39. A composition according to claim 36 wherein said base polymer iselastomeric. I

40. A composition according to claim 36 wherein said base polymer is ablend of elastomeric and plastic polymers.

41. A composition according to claim 37 wherein said unsaturatedcarboxylic acid is acrylic acid or a derivative thereof.

42. A composition according to claim 37 wherein said unsaturatedcarboxylic acid or a derivative thereof is glycidyl acrylate or maleicanhydride.

43. A composition according to claim 38 wherein said grafted compound isselected from the group consisting of acrylic acid, glycidyl acrylate,maleic anhydride or a derivative thereof.

44. A composition according to claim 39 wherein said grafted compound isselected from the group consisting of acrylic acid, glycidyl acrylate,maleic anhydride or a derivative thereof.

45. A reactor apparatus which comprises in combination:

a. a hollow extruder barrel with exterior, interior, be-

ginning, middle and final portions;

b. an extruder screw means having a root of varying cross-sectional areaoperably mounted within said barrel to advance material through saidbarrel;

c. a reaction chamber in the middle portion of said barrel having aninitial portion, said initial portion of said chamber beingcharacterized by a decreased cross-sectional area of said screw root;and

d. orifice means communicating between said initial chamber portion andsaid exterior portion of said barrel.

46. A reactor apparatus according to claim 45 wherein said final portionof the reaction chamber has a root cross-sectional area only slightlysmaller than the internal cross-sectional area of said barrel, wherebygaseous materials within said chamber are prevented from easily escapingfrom said chamber.

47. A reactor apparatus which comprises in combination:

a. a hollow extruder barrel with exterior, interior, be-

ginning, middle and final portions;

b. extruder screw means having a root of varying cross-sectional areaoperably mounted within said barrel to advance material through saidbarrel;

c. a high-shear, thin film reaction chamber in the middle of said barrelhaving an initial portion defined by an increased cross-sectional thinfilm forming means screw root to shearingly engage said material betweensaid barrel and said segment; and

d. orifice means communicating between said initial chamber portion andsaid exterior portion of said barrel.

48. A reactor apparatus according to claim 47 wherein said reactionchamber has a final portion delined by a root cross-sectional area onlyslightly smaller than said interior crosssectional area of said barrel.whereby gaseous materials formed in said chamber are prevented fromeasily escaping from said chamber.

49. A reactor apparatus according to claim 47 wherein said thin-filmforming means is a cylinder or cone segment means having an output endand an input end longitudinally mounted in said barrel to shearinglyengage a fluid between said barrel and said cylinder comprising:

l. input grove means on the surface at the input end of said segmentmeans terminating in dead ends before the output end;

2. output grove means on the surface of said cylinder or cone means atthe output end of said segment, terminating before reaching said inputend; and

3. thin-film barrier means intermediate said grove, said barrier meansnot contacting the interior wall of said barrel.

50. A composition according to claim 42 wherein said unsaturatedcarboxylic acid or a derivative thereof is glycidyl acrylate.

51. The composition of claim 36 which has an MFR of from 11 to 250 andsaid MFR being at least higher than the MFR of said base polymer.

52. A composition according to claim 36 having an MFR of 21 to lOO and adie swell of at least 0. l of a unit less than that of the base polymer.

53. A composition according to claim 52 having a die swell of at least0.15 of a unit less than that of the base polymer.

54. A composition according to claim 51 in which the grafted monomer isglycidyl acrylate.

55. A composition according to claim 36 wherein said polyolefin ispolypropylene and said grafted monomer is glycidyl acrylate.

56. A composition according to claim 36 wherein said polyolefin ispolypropylene and said monomer is acrylic acid.

57. A grafted C,-, to C polyolefin comprising from 0.02 to 20 weightpercent of a grafted component and having a melt-flow rate (MFR) of from3 to 1,000 wherein said grafted polyolefin has been prepared by freeradical attack on a base polymer in the presence of a monomer or agraftable reactive compound, wherein said base polymer has an MFR offrom 0.3 to 0.9 and the MFR of said grafted polyolefin is at least1,000% more than the MFR of said base polymer and the die swell of saidgrafted polyolefin is at least 0.05 less than that of said basepolyolefin.

58. A grafted C to C polyolefin comprising from 0.02 to 20 weightpercent of a grafted component and having a melt-flow rate (MFR) of from5 to 1,000 wherein said grafted polyolefin has been prepared by freeradical attack on a base polymer in the presence of a monomer or agraftable reactive compound, wherein said base polymer has an MFR offrom 0.91 to 5.0 and the MFR of said grafted polyolefin is at least 700%more than the MFR of said base polymer and the die swell of said graftedpolyolefin is at least 0. l0 less than that of said base polyolefin.

59. A grafted C to C polyolefin comprising from 0.02 to 20 weightpercent of a grafted component and having a melt-flow rate (MFR) of from20 to 300 wherein said grafted polyolefin has been prepared by freeradical attack on a base polymer in the presence of a minor or agraftable reactive compound, wherein said base polymer has an MFR offrom 5.01 to and the MFR of said grafted polyolefin is at least 400%more than the MFR of said base polymer and the die swell of said graftedpolyolefin is at least 0.10 less than that of said base polyolefin.

60. A grafted C to C polyolefin comprising from 0.02 to weight percentof a grafted component and having a melt-flow rate (MFR) of from 20 to300 wherein said grafted polyolefin has been prepared by free radicalattack on a base polymer in the presence of a monomer or a graftablereactive compound, wherein said base polymer has an MFR of from 10.1 to150 and the MFR of said grafted polyolefin is at least 100% more thanthe MFR of said base polymer and the die swell of said graftedpolyolefin is at least 0.10 less than that of said base polyolefin.

61. A grafted C to C polyolefin comprising from 0.02 to 20 weightpercent of a grafted component and having a melt-flow rate (MFR) of from5 to 300 wherein said grafted polyolefin has been prepared by freeradical attack on a base polymer in the presence of a monomer or agraftable reactive compound, wherein said base polymer has an MFR offrom 0.91 to 5.0 and the MFR of said grafted polyolefin is at least 900%more than the MFR of said base polymer and the die swell of said graftedpolyolefin is at least 0.15 less than that of said base polyolefin.

62. A grafted polymeric composition, prepared from a base polymer,comprising from 0.02m 20 weight percent of grafted compound and having amelt flow rate of from 3 to 1,000 and at least 50% higher than said basepolymer and a die swell of at least 0.05 unit less than that of saidbase polymer, wherein said grafted composition has been prepared by theprocess of claim 19.

63. A grafted polymeric composition, prepared from a base polymer,comprising from 0.02 to 20 weight percent of grafted compound and havinga melt flow rate of from 3 to 1,000 and at least 90 higher than saidbase polymer and a die swell of at least 0.05 unit less than that ofsaid polymer, wherein said grafted composition has been prepared by theprocess of claim 20.

64. A composition according to claim 62 wherein said base polymer ispolystyrene or a C to C polyolefin and said grafted portion of saidpolymer is derived from unsaturated carboxylic acids or theirderivatives.

65. A composition according to claim 62 wherein said base polymer isplastic.

66. A composition according to claim 62 wherein said base polymer iselastomeric.

67. A composition according to claim 62 wherein said base polymer is ablend of elastomeric and plastic polymers.

68. A composition according to claim 62 wherein said unsaturatedcarboxylic acid is acrylic acid or a derivative thereof.

69. A composition according to claim 62 wherein said unsaturatedcarboxylic acid or a derivative thereof is glycidyl acrylate or maleicanhydride.

70. A composition according to claim 66 wherein said grafted compound isselected from the group consisting of acrylic acid, glycidyl acrylate,maleic anhydride or a derivative thereof.

71. A composition according to claim 62 wherein said grafted compound isselected from the group consisting of acrylic acid, glycidyl acrylate,maleic anhydride or a derivative thereof.

72. A process according to claim 1 wherein said monomer is himicanhydride or acid.

73. A process according to claim 19 wherein said monomer is himicanhydride or acid.

74. A composition according to claim 64 wherein said unsaturatedcarboxylic acid or a derivative thereof is himic anhydride or acid.

75. The composition of claim 62 which has an MFR of from 1 l to 250 andsaid MFR being at least 150% higher than the MFR of said base polymer.

76. A composition according to claim 62 having an MFR of2l to 100 and adie swell of at least 0.1 of a unit less than that of the base polymer.

77. A composition according to claim 76 having a die swell of at least0.15 of a unit less than that of the base polymer.

78. A composition according to claim in which the grafted monomer isglycidyl acrylate.

79. A composition according to claim 64 wherein said polyolefin ispolypropylene and said grafted monomer is glycidyl acrylate.

80. A composition according to claim 64 wherein said polyolefin ispolypropylene and said monomer is acrylic acid.

2. A process according to claim 1 wherein said polymer is athermoplastic polymer.
 2. output grove means on the surface of saidcylinder or cone means at the output end of said segment, terminatingbefore reaching said input end; and
 3. thin-film barrier meansintermediate said grove, said barrier means not contacting the interiorwall of said barrel.
 3. A process according to claim 2 wherein saidpolymer is a C2 to C8 olefin polymer.
 4. A process according to claim 3wherein said polymer is either high or low density polyethylene.
 5. Aprocess according to claim 3 wherein said polymer is polypropylene.
 6. Aprocess according to claim 3 wherein said polymer is chosen from thegroup consisting of polymethyl pentene, isotactic polypropylene,polyallomers, polybutylene and mixtures thereof.
 7. A process accordingto claim 1 wherein said polymer is an elastomer.
 8. A process accordingto claim 7 wherein said elastomer is an ethylene-propylene copolymer oran ethylene-propylene diene terpolymer.
 9. A process according to claim1 wherein said monomer is unsaturated and has carboxylic acidfunctionality or a derivative of said acid functionality.
 10. A processaccording to claim 1 wherein said monomer is acrylic acid or one of itsderivatives.
 11. A process according to claim 1 wherein said monomer ismaleic anhydride or one of its derivatives.
 12. A process according toclaim 9 wherein the modified polymer resulting from the process issubsequently modified by subsequent reactions chosen from the groupconsisting of esterification, neutralization, amidization andimidization.
 13. A process according to claim 1 wherein saidfree-radical initiator is introduced in the absence of free-radicalreactive monomers.
 14. A process according to claim 1 wherein saidfree-radical initiator is introduced in the presence of free-radicalractive monomers.
 15. A process according to claim 1 wherein the initialportion of said reaction zone is at a relatively low pressure ascompared to the rest of said reaction zone.
 16. A process according toclaim 1 wherein said polymer is a blend of a plastic and an elastomer.17. A process according to claim 1 wherein said monomer is chosen fromthe group consisting of acrylic acid, glycidyl acrylate and maleicanhydride, and said polymer is polypropylene.
 18. A process according toclaim 1 wherein said monomer is chosen from the group consisting ofacrylic acid, glycidyl acrylate and maleic anhydride, and said polymeris an ethylene-containing polymer.
 19. A process for modifying therheological or chemical-rheological properties of a polymer which isnormally solid at room temperature, which comprises in combination thesteps of: a. introducing said polymer into an extruder with a movingpositive displacement screw of varying root cross-sectional area todefine a reaction zone; b. generating an above-atmospheric pressurewithin said extruder as said polymer is conveyed therethrough; c.applying sufficient heat in addition to working said polymer, to convertit into its fluid form; d. conveying said fluid polymer through theinitial portion of said reaction zone whereby said fluid polymer isforced into a relatively thin, as compared to the portion of saidextruder just prior to said initial portion of said reaction zone, fluidfilm under high shear; e. introducing into said initial portion of saidreaction zone while said polymer is in a thin-film, high-shear statesufficient of a material selected from the group consisting of: i. amonomer or monomers; ii. a free-radical initiator; iii. a combination ofthe foregoing; to measurably change either the rheological or chemicalproperties or both of said properties; and f. conveying the resultantmodified polymer through the remainder of the extrusion process.
 20. Amethod according to claim 19 wherein said initial portion of saidreaction zone is characterized by a relatively large screw rootcross-sectional area as compared to the screw root cross-sectional areaimmediately preceding said reaction zone.
 21. A process according toclaim 19 wherein said polymer is a C2 to C8 olefin polymer.
 22. Aprocess according to claim 21 wherein said polymer is either high or lowdensity polyethylene.
 23. A process according to claim 21 wherein saidpolymer is polypropylene.
 24. A process according to claim 21 whereinsaid polymer is chosen from the group consisting of polymethyl pentene,isotactic polypropylene, polyallomers, polybutylene and mixturesthereof.
 25. A process according to claim 19 wherein said polymer is anelastomer.
 26. A process according to claim 25 wherein said elastomer isan ethylene-propylene copolymer or an ethylene-propylene dieneterpolymer.
 27. A process according to claim 19 wherein said monomer isunsaturated and has carboxylic functionality or a derivative of saidacid functionality.
 28. A process according to claim 19 wherein saidmonomer is acrylic acid or one of its derivatives.
 29. A processaccording to claim 19 wherein said monomer is glycidyl acrylate ormaleic anhydride or one of its derivatives.
 30. A process according toclaim 27 wherein the modified polymer resulting from the process issubsequently modified by subsequent reactions chosen from the groupconsisting of esterification, neutralization, amidization andimidization.
 31. A process according to claim 19 wherein saidfree-radical initiator is introduced in the absence of free-radicalreactive monomers.
 32. A process according to claim 19 wherein saidfree-radical initiator is introduced in the presence of free-radicalreactive monomers.
 33. A process according to claim 19 wherein saidpolymer is a blend of a plastic and an elastomer.
 34. A processaccording to claim 19 wherein said monomer is chosen from the groupconsisting of acrylic acid, glycidyl acrylate and maleic anhydride, andsaid polymer is polypropylene.
 35. A process according to claim 19wherein said monomer is chosen from the group consisting of acrylicacid, glycidyl acrylate and maleic anhydride, and said polymer is anethylene-containing polymer.
 36. A grafted polymeric composition,prepared from a base polymer, comprising from 0.02 to 20 weight percentof grafted compound and having a melt flow rate of from 3 to 1,000 andat least 50% higher than said base polymer and a die swell of at least0.05 unit less than that of said base polymer wherein said graftedcomposition has been prepared by the process of claim
 1. 37. Acomposition according to claim 36 wherein said base polymer ispolystyrene or a C3 to C10 polyolefin and said grafted portion of saidpolymer is derived from unsaturated carboxylic acids or theirderivatives.
 38. A composition according to claim 36 wherein said basepolymer is plastic.
 39. A composition according to claim 36 wherein saidbase polymer is elastomeric.
 40. A composition according to claim 36wherein said base polymer is a blend of elastomeric and plasticpolymers.
 41. A composition according to claim 37 wherein saidunsaturated carboxylic acid is acrylic acid or a derivative thereof. 42.A composition according to claim 37 wherein said unsaturated carboxylicacid or a derivative thereof is glycidyl acrylate or maleic anhydride.43. A composition according to claim 38 wherein said grafted compound isselected from the group consisting of acrylic acid, glycidyl acrylate,maleic anhydride or a derivative thereof.
 44. A composition according toclaim 39 wherein said grafted compound is selected from the groupconsisting of acrylic acid, glycidyl acrylate, maleic anhydride or aderivative thereof.
 45. A reactor apparatus which comprises incombination: a. a hollow extruder barrel with exterior, interior,beginning, middle and final portions; b. an extruder screw means havinga root of varying cross-sectional area operably mounted within saidbarrel to advance material through said barrel; c. a reaction chamber inthe middle portion of said barrel having an initial portion, saidinitial portion of said chamber being characterized by a decreasedcross-sectional area of said screw root; and d. orifice meanscommunicating between said initial chamber portion and said exteriorportion of said barrel.
 46. A reactor apparatus according to claim 45wherein said final portion of the reaction chamber has a rootcross-sectional area only slightly smaller than the internalcross-sectional area of said barrel, whereby gaseous materials withinsaid chamber are prevented from easily escaping from said chamber.
 47. Areactor apparatus which comprises in combination: a. a hollow extruderbarrel with exterior, interior, beginning, middle and final portions; b.extruder screw means having a root of varying cross-sectional areaoperably mounted within said barrel to advance material through saidbarrel; c. a high-shear, thin film reaction chamber in the middle ofsaid barrel having an initial portion defined by an increasedcross-sectional thin film forming means screw root to shearingly engagesaid material between said barrel and said segment; and d. orifice meanscommunicating between said initial chamber portion and said exteriorportion of said barrel.
 48. A reactor apparatus according to claim 47wherein said reaction chamber has a final portion defined by a rootcross-sectional area only slightly smaller than said interiorcross-sectional area of said barrel, whereby gaseous materials formed insaid chamber are prevented from easily escaping from said chamber.
 49. Areactor apparatus according to claim 47 wherein said thin-film formingmeans is a cylinder or cone segment means having an output end and aninput end longitudinally mounted in said barrel to shearingly engage afluid between said barrel and said cylinder comprising:
 50. Acomposition according to claim 42 wherein said unsaturated carboxylicacid or a derivative thereof is glycidyl acrylate.
 51. The compositionof claim 36 which has an MFR of from 11 to 250 and said MFR being atleast 150% higher than the MFR of said base polymer.
 52. A compositionaccording to claim 36 having an MFR of 21 to 100 and a die swell of atleast 0.1 of a unit less than that of the base polymer.
 53. Acomposition according to claim 52 having a die swell of at least 0.15 ofa unit less than that of the base polymer.
 54. A composition accordingto claim 51 in which the grafted monomer is glycidyl acrylate.
 55. Acomposition according to claim 36 wherein said polyolefin ispolypropylene and said grafted monomer is glycidyl acrylate.
 56. Acomposition according to claim 36 wherein said polyolefin ispolypropylene and said monomer is acrylic acid.
 57. A grafted C3 to C10polyolefin comprising from 0.02 to 20 weight percent of a graftedcomponent and having a melt-flow rate (MFR) of from 3 to 1,000 whereinsaid grafted polyolefin has been prepared by free radical attack on abase polymer in the presence of a monomer or a graftable reactivecompound, wherein said base polymer has an MFR of from 0.3 to 0.9 andthe MFR of said grafted polyolefin is at least 1,000% more than the MFRof said base polymer and the die swell of said grafted polyolefin is atleast 0.05 less than that of said base polyolefin.
 58. A grafted C3 toC10 polyolefin comprising from 0.02 to 20 weight percent of a graftedcomponent and having a melt-flow rate (MFR) of from 5 to 1,000 whereinsaid grafted polyolefin has been prepared by free radical attack on abase polymer in the presence of a monomer or a graftable reactivecompound, wherein said base polymer has an MFR of from 0.91 to 5.0 andthe MFR of said grafted polyolefin is at least 700% more than the MFR ofsaid base polymer and the die swell of said grafted polyolefin is atleast 0.10 less than that of said base polyolefin.
 59. A grafted C3 toC10 polyolefin comprising from 0.02 to 20 weight percent of a graftedcomponent and having a melt-flow rate (MFR) of from 20 to 300 whereinsaid grafted polyolefin has been prepared by free radical attack on abase polymer in the presence of a minor or a graftable reactivecompound, wherein said base polymer has an MFR of from 5.01 to 10 andthe MFR of said grafted polyolefin is at least 400% more than the MFR ofsaid base polymer and the die swell of said grafted polyolefin is atleast 0.10 less than that of said base polyolefin.
 60. A grafted C3 toC10 polyolefin comprising from 0.02 to 20 weight percent of a graftedcomponent and having a melt-flow rate (MFR) of from 20 to 300 whereinsaid grafted polyolefin has been prepared by free radical attack on abase polymer in the presence of a monomer or a graftable reactivecompound, wherein said base polymer has an MFR of from 10.1 to 150 andthe MFR of said grafted polyolefin is at least 100% more than the MFR ofsaid base polymer and the die swell of said grafted polyolefin is atleast 0.10 less than that of said base polyolefin.
 61. A grafted C3 toC10 polyolefin comprising from 0.02 to 20 weight percent of a graftedcomponent and having a melt-flow rate (MFR) of from 5 to 300 whereinsaid grafted polyolefin has been prepared by free radical attack on abase polymer in the presence of a monomer or a graftable reactivecompound, wherein said base polymer has an MFR of from 0.91 to 5.0 andthe MFR of said grafted polyolefin is at least 900% more than the MFR ofsaid base polymer and the die swell of said grafted polyolefin is atleast 0.15 less than that of said base polyolefin.
 62. A graftedpolymeric composition, prepared from a base polymer, comprising from0.02 to 20 weight percent of grafted compound and having a melt flowrate of from 3 to 1,000 and at least 50% higher than said base polymerand a die swell of at least 0.05 unit less than that of said basepolymer, wherein said grafted composition has been prepared by theprocess of claim
 19. 63. A grafted polymeric composition, prepared froma base polymer, comprising from 0.02 to 20 weight percent of graftedcompound and having a melt flow rate of from 3 to 1,000 and at least 90higher than said base polymer and a die swell of at least 0.05 unit lessthan that of said polymer, wherein said grafted composition has beenprepared by the process of claim
 20. 64. A composition according toclaim 62 wherein said base polymer is polystyrene or a C3 to C10polyolefin and said grafted portion of said polymer is derived fromunsaturated carboxylic acids or their derivatives.
 65. A compositionaccording to claim 62 wherein said base polymer is plastic.
 66. Acomposition according to claim 62 wherein said base polymer iselastomeric.
 67. A composition according to claim 62 wherein said basepolymer is a blend of elastomeric and plastic polymers.
 68. Acomposition according to claim 62 wherein said unsaturated carboxylicacid is acrylic acid or a derivative thereof.
 69. A compositionaccording to claim 62 wherein said unsaturated carboxylic acid or aderivative thereof is glycidyl acrylate or maleic anhydride.
 70. Acomposition according to claim 66 wherein said grafted compound iSselected from the group consisting of acrylic acid, glycidyl acrylate,maleic anhydride or a derivative thereof.
 71. A composition according toclaim 62 wherein said grafted compound is selected from the groupconsisting of acrylic acid, glycidyl acrylate, maleic anhydride or aderivative thereof.
 72. A process according to claim 1 wherein saidmonomer is himic anhydride or acid.
 73. A process according to claim 19wherein said monomer is himic anhydride or acid.
 74. A compositionaccording to claim 64 wherein said unsaturated carboxylic acid or aderivative thereof is himic anhydride or acid.
 75. The composition ofclaim 62 which has an MFR of from 11 to 250 and said MFR being at least150% higher than the MFR of said base polymer.
 76. A compositionaccording to claim 62 having an MFR of 21 to 100 and a die swell of atleast 0.1 of a unit less than that of the base polymer.
 77. Acomposition according to claim 76 having a die swell of at least 0.15 ofa unit less than that of the base polymer.
 78. A composition accordingto claim 75 in which the grafted monomer is glycidyl acrylate.
 79. Acomposition according to claim 64 wherein said polyolefin ispolypropylene and said grafted monomer is glycidyl acrylate.
 80. Acomposition according to claim 64 wherein said polyolefin ispolypropylene and said monomer is acrylic acid.